Conventionally, there is known an optical scanning device in which at least a part of a vibration body having a reflector mirror part formed on a silicon substrate is vibrated and a direction of a light beam incident to the reflector mirror part is changed to a reflection direction so that the reflected light beam is scanned. In the optical scanning device, the vibration body includes a first spring part connected to the reflector mirror part to generate torsional vibration, and a plurality of second spring parts each connected to the first spring part to generate both bending vibration and torsional vibration. All the other ends of the second spring parts are connected and fixed to a fixed frame part, and the optical scanning device includes a plurality of drive sources to vibrate the respective second spring parts. See Patent Document 1 listed below.
In the optical scanning device disclosed in Patent Document 1, each of the second spring parts has an elastic modulus which is the same as that of the first spring part, and has a cross-sectional shape which causes the second sprint part to elastically deform more easily than the first spring part. The displacement of the drive source generates bending vibration in a thickness direction of a plate member which constitutes the second spring part, and the bending vibration is transmitted to the first spring part as a torsional vibration from the portion of the second spring part connected to the first spring part. The load needed for vibrating the reflector mirror part is distributed to the first spring part and the second spring parts.